KR20080064123A - Cigarette package provided with internal envelops made from polymer film - Google Patents

Abstract

The invention relates to a single-or multilayer biaxially oriented film, which contains 70-100 % by weight polymer consisting of at least one type of aliphatic hydroxycarboxylic acid, and which is used in the form of an inner liner of a cigarette package.

Description

Cigarette wrapper with inner skin made of polymer film {CIGARETTE PACKAGE PROVIDED WITH INTERNAL ENVELOPS MADE FROM POLYMER FILM}

The present invention relates to a tobacco wrapper comprising at least one outer wrapper and an inner wrapper for tobacco. The invention further relates to an inner liner.

Tobacco wrap is conventionally made in such a way as to wrap the contents of the wrap, i. In the prior art, this inner wrapper consists of a cut sheet of aluminum foil, an aluminum-paper laminate or a piece of metalized paper. Such inner wrappers are often printed or embossed. Early cutting sheets are now replaced by inner wrappers made of paper. The inner wrapper is often printed or metallized and, if necessary, combined with embossment on the outside.

When manufacturing the wrapper, the cigarettes are packaged with such an inner wrapper, the so-called inner liner, and the packaged tobacco bundles are folded together, for example by flip-top lid wrappers or paper labels, by an outer wrapper, packaging machine. All.

The inner liner may be made of printed paper, metallized paper or other thin sheet of material. This material is peeled off the roll and placed on the packaging machine, and cut to the appropriate length. If necessary, selected perforations are made to create a target cut-off point that allows for selected tear opening of the inner liner upon first opening of the package.

Paper and metal films are particularly advantageous because of their folding properties and tearing properties. In this type of use, the strip of material must have good folding properties (dead-fold), ensuring that the outer wrapper is packed tightly enough to remain in place until the place where it is placed. In addition, the tearing property plays an important role in that controlled opening of the liner is ensured. Finally, the cut should be characterized by being completely flat so that handling of the strip of material is not hindered by curling.

This property is suitably satisfied by paper and metallized paper. Films made from thermoplastic polymers lack inherent folding properties and are generally not suitable materials for this method of use. Furthermore, plastic films in the form of small cuts tend to roll up, that is, these cuts themselves roll up along or across the length of the film strip.

Nevertheless, because plastic films are often advantageous over paper both in terms of environmental aspects and in terms of cost, replacement of paper is a constant demand for film manufacturers in various applications.

In essence, the present invention has made it possible to make films that meet the needs of these applications suitable for use as inner liners in tobacco wrappers.

This is solved by using a biaxially oriented film, single layer or multilayer, as the inner liner of the tobacco wrapper, which film contains 70 to 100% by weight of a polymer made of at least one aliphatic hydroxy carboxylic acid.

The invention is particularly used for flip packaging containers and soft packaging. Inner liners made of polyhydroxycarboxylic acid films, preferably PSA films, are particularly suitable for flip packaging containers. Such containers are conventionally made of thin cards. Part of the container serves to extract the entire bunch of cigarettes surrounded by the package contents, i.e. folded inner wrapper made of polyhydroxycarboxylic acid or PSA. The lid disposed on the back side of the container is connected to the container by a fold line. A more detailed description of an embodiment of flip packs is known and described, for example, in DE 43 33 462, which description is hereby incorporated by reference.

The bundle of cigarettes, ie the package contents, is surrounded on all sides by an inner wrapper according to the invention. The unit so represented as the package contents is a tobacco block. According to the invention, a film made of polyhydroxycarboxylic acid, preferably a PLA film, is introduced into the tobacco wrapper for producing such tobacco blocks.

The film is cut to a suitable width for this purpose, peeled off as a rim, placed on a packaging machine, and cut into suitable lengths. The shape of the cut depends on the type of folding you are using. For example, the cut film is placed around the bundle of cigarettes according to the principle of folding. The front and back are connected to a continuous, closed bottom. The upper end wall is likewise folded to form an inner pointed corner and a trapezoidal pointed edge.

In a further embodiment, the inner wrapper of the upper region may have a draw strip, so-called flaps. To this end, a tear line or other kind of weakening line is made over the entire width of the cut portion. When opening the package for the first time, the stretch strip is separated by hooking on the outer sharp edges.

The cut part is generally separated from the strip of material in such a way that the cut part lies in the longitudinal direction. The strips of material can be provided with a printing surface if necessary, and it is advantageous to arrange them at intervals between the strips in a direction extending along the length of the material. The cross cuts that divide the cuts are placed across the film vertically. Accurate positioning of the dividing line can be performed by print mark control due to printer imprints.

Alternatively, the cut portion can be done in such a way that the width of the strip of film corresponds to the length of the cut portion. In this arrangement, the cut portions are aligned perpendicular to the length of the strip of material. In this case, the strip of material has a continuous strip of printing on both sides, in particular of varying widths.

The cutting portion, and the technique of folding the inner liner, the unit for printing the cutting portion and further details are known in the art and are described, for example, in DE 201 20 977 or DE 43 33 462 or DE, which is hereby incorporated by reference. 25 11 241.

Packaging with an inner liner constructed in the manner described generally further comprises an outer wrapper made of a film, in particular a polypropylene film or cellophane.

According to the present invention, the inner liner is made of a biaxially oriented film and can be characterized by one or several layers. The main composition of this film is a polymer made of at least one aliphatic hydroxycarboxylic acid. Generally, the film comprises at least 70-100% aliphatic polyhydroxycarboxylic acid, preferably PSA. Preference is given to examples made in each case from 80 to 99% by weight, preferably from 85 to 95% by weight, of the specified polymer relative to the weight of the film.

Surprisingly, films made of polyhydroxycarboxylic acids, preferably PLA, are excellent for use as inner liners. It has been found that the film holds the bundle of cigarettes in place after close contact. The film exhibits cleavage while being handled in a packaging machine. Surprisingly, the cuts hardly and sometimes never curled up, proving to avoid the problems of other thermoplastic films. Furthermore, films are particularly advantageous because they provide very stable mobility even under varying climatic conditions. Compared with paper, it shows that fluctuating temperature or fluctuating humidity has little effect on the film and its properties, and does not affect the use as an inner liner, and can always be treated equally well.

Both monolayer films and multilayer films made of aliphatic polyhydroxycarboxylic acids are suitable for use according to the invention. Multilayer films generally consist of a thick base layer that features the largest layer thickness and constitutes 60 to <100% of the total thickness of the film. This base layer preferably has top layer (s) on both sides but only on one side if necessary. In a further embodiment, further interlayers or coatings of the outer surface of the multilayer film are possible, through which a four or five layer film is coated or uncoated. The thickness of the top layer is generally in the range from 0.5 μm to 10 μm, preferably from 0.5 to 6 μm, in particular from 1 to 3 μm. The total thickness of the film according to the invention is in the range of 20 to 100 μm, preferably 25 to 80 μm, in particular 30 to 60 μm. The top layer is the layer that forms the outer layer of the film. The intermediate layer is naturally attached between the base layer and the top layer. The following examples for the layers of the film are considered similarly in the same way as the single layer embodiments of the film.

Surprisingly, films having a minimum thickness of 20 μm are particularly advantageous for use as the inner liner according to the invention. If the thickness of the film is less than 20 μm, congestion occurs in the machine. It has surprisingly been found that the film works much better for the use according to the invention. If the film thickness is too large, the film exhibits too large reset force, causing the packaged tobacco to come out of the bundle before the external flip pack can be applied. Therefore, it should not exceed the maximum thickness of 100㎛.

The film, and if necessary the individual layers of the film, comprises 70 to about 100% by weight, preferably 80 to 98% by weight of a polymer made of at least one aliphatic hydroxycarboxylic acid (also referred to as PHC or polyhydroxycarboxylic acid). do. This means homopolymers or mixed polymers composed of polymer units of aliphatic hydroxycarboxylic acids. Among the PHCs suitable for the present invention, polylactic acid is particularly suitable. This is hereinafter referred to as poly lactic acid (PLA). Here, both homopolymers consisting solely of lactic acid, and also mixed polymers comprising primarily lactic acid units (> 50%) combined with other aliphatic hydroxylactic acid units, are meant for the term PSA.

As monomers of aliphatic polyhydroxycarboxylic acids (PHC), aliphatic mono-, di- or trihydroxycarboxylic acids, or dimer cyclic esters thereof are suitable, of which D- or L-type lactic acid is preferred. . Polymers of this kind are known in the art and are commercially available. The production of polylactic acid is likewise described in the prior art and occurs by catalytic ring-opening polymerization of lactide (1,4-dioxane-3,6-dimethyl 2,5-dione). Dimeric cyclic esters of lactic acid, hence PSA, are often also referred to as polylactides. The preparation of PSAs is described in US 5,208,297, US 5,247,058 or US 5,357,035.

Preference is given to polylactic acid which consists solely of lactic acid units. In addition, PSA homopolymers comprising 80-100% by weight of L-lactic acid units corresponding to 0-20% by weight of D-lactic acid units are particularly preferred. Even higher concentrations of D-lactic acid units can be included as comonomers to reduce microcrystals. If desired, the polylactic acid can be used as a comonomer of lactic acid to form several aliphatic polyhydroxycarboxylic acid units, such as glycolic acid units, 3-hydroxypropanoic acid units, 2,2-dimethyl-3-hydroxypropanoic acid units or at most It may be further characterized by higher homologues of hydroxycarboxylic acids having five carbon atoms.

The melting point is 110 to 170 ° C., preferably 125 to 165 ° C., and the melt flow index (DIN measurement 53 735 at 190 ° C. and 2.16 N load) is 1 to 50 g / 10 minutes, preferably 1 to Preference is given to lactic acid polymers (PLA) which are 30 g / 10 min. The molecular weight of the PLA is in the range of at least 10000 to 500000 (average calculation), preferably 50000 to 300000 (average calculation). The glass transition temperature (Tg) is in the range of 40 to 100 ° C, preferably 40 to 80 ° C.

The individual layers of the film each comprise 70 to about 100%, preferably 80 to 98%, by weight of the aforementioned polymers, and, if necessary, also with neutralizing agents, stabilizers, lubricants, static inhibitors and fillers; Such as additional additives. They are advantageously added to the polymer or polymer mixture prior to melting. Phosphorous binders such as phosphoric acid or phosphate esters are for example introduced as stabilizers. The individual layers are characterized by essentially the same composition with respect to the polymer and the additives. Typically, the composition of this base layer is different from that of the remaining layers. In particular, additives such as antiblocking agents or lubricants are added to the top layer, while fillers or pigments are preferably added to the base layer. Nevertheless, the structure and composition of the individual layers of the film can vary within wide boundaries.

Transparent and white examples without vacuoles are known to be particularly well suited for this use. For polypropylene, it is known that the opaque PP film with the steel of the base layer is characterized by better folding properties than the transparent PP film. In addition, the PLA-free PLA film surprisingly shows very good folding properties compared to the Examples with cast steel in this application. In the sense of the present invention, a transparent film is to be understood as a transparent film having a light transmittance of at least 75%, preferably 95% according to ASTM-D 1003-77. The white PLA film is colored white by the addition of a white pigment, but without pores. Such an embodiment generally comprises TiO ₂ in an amount of 1-12% by weight in at least one layer and several layers if necessary. In essence, TiO ₂ can be added in this amount to one or two top layers or also to one or two intermediate layers.

It is also possible to add essentially opaque or white-opaque embodiments of the film. Such films comprise a vacuole-initiating filler in the base layer, for example a cycloolefin copolymer (opaque film) and, if necessary, additional pigments (white-opaque film). In this case, TiO ₂ is also preferred as a pigment and is introduced in each case with respect to the base layer in an amount of up to 10% by weight, preferably 1 to 8% by weight.

If desired, the films can be coated to further optimize their properties. Common coatings are those that act as adhesive-improving, slippery-improving or peeling off. If desired, such additional coatings may be applied over the in-line coating with an aqueous or non-aqueous dispersant prior to lateral stretching or off-line.

In further embodiments, the film may be metallized as an inner liner prior to use. In use as an inner-liner, the metallized side forms the visible side. In a further embodiment, the film can be metallized on both sides. This embodiment has the advantage of preventing direct contact between the cigarette and the film, such that no loss of taste of the cigarette can occur, or rather broadly protected.

In a further embodiment, the metallized or non-metallized film may additionally have embossments that have decorative features on the one hand and provide further improved flatness. Surprisingly, after metallization and printing, the film can only be treated as much as the paper inner-liner used so far. In addition, embossed and metallized films are almost similar to the general appearance of metallized paper.

PHC films are made according to a coextrusion procedure known per se. Within the scope of this procedure, the melt (s) corresponding to the layers of film are coextruded past the flat die, and the multilayer film thus obtained is peeled off for curing on one or several roller (s) and subsequently The film is biaxially stretched (oriented), the biaxially-stretched film is heat set and, if necessary, corona- or flame-treated on the surface to be treated.

Biaxial stretching is generally performed sequentially. By doing so, the stretching preferably takes place first in the longitudinal direction (ie machine direction, = MD direction) and then in the lateral direction (ie perpendicular to the machine direction, = TD direction). This results in the orientation of the molecular chains. Stretching in the longitudinal direction is preferably caused by two rollers moving at different speeds, corresponding to the desired draw ratio. For lateral stretching, the clip frame is commonly used. Further techniques of film production are carried out according to the example of flat film extrusion by subsequent sequential stretching.

The melt (s) is compressed through a flat die (sheet die) and one or several outfeed rollers at a temperature of 10 to 100 ° C., preferably 20 to 80 ° C., to cool and cure the compressed film. It is detached from.

The film thus obtained is then stretched along the extrusion direction and across the extrusion direction. The stretching in the longitudinal direction is advantageously carried out at the stretching temperature of the stretching roller, preferably from 40 to 130 ° C, preferably from 50 to 100 ° C, due to the two rollers moving at different speeds, corresponding to the desired draw ratio. Can be; Stretching in the lateral direction can be carried out at 50 to 130 ° C, preferably 60 to 120 ° C, by means of the clip frame. The stretching ratio in the longitudinal direction may vary within the range of 1.5 to 8. In the production of a film with a base layer comprising a steel-starting filler, a high draw ratio in the longitudinal direction of 3 to 6 is preferred, while a film with a transparent base layer is preferably drawn within the range of 1.5 to 3.5. The stretching ratio in the lateral direction is preferably in the range of 3 to 10, preferably 4 to 7.

Thermal fixation of the film (heat treatment) is applied to the stretching of the film, where the film continues to converge at a temperature of 60 to 150 ° C. for up to about 0.1 to 10 seconds (maximum 25% convergence). As a result, the film is wound in a conventional manner by a batcher.

The following measurements were used to characterize the raw material and the film:

The invention will be explained below on the basis of the following examples.

Example 1:

Transparent three-layer PLA films having a thickness of about 30 μm were prepared by extrusion and subsequent orientation in the longitudinal and lateral directions. Almost 100% by weight of the base layer consists of polyacetic acid having a melting point of about 160 ° C. The layer additionally contained stabilizers and neutralizers in conventional amounts. The sealable top layers are all composed essentially of amorphous polylactic acid, wherein the polylactic acid is characterized by an L / D ratio of about 40/60. In addition, the top layer contained 0.1 wt% of SiO ₂ -based particles as the block-blocking agent. The thickness of each of the top layers was 2.5 μm.

The manufacturing conditions at the individual procedure stage are:

Extrusion: temperature 170-200 ℃

Temperature of discharge roller: 60 ℃

Longitudinal Stretching: Temperature: 68 ℃

Portrait draw ratio: 2.0

Lateral drawing: Temperature: 88 ° C

Lateral draw ratio (effective): 5.5

Fixed: temperature 75 ℃

Convergence: 5%

Example 2:

The film was prepared as described in Example 1. In contrast to Example 1, no top layer was attached. Other compositions and preparation conditions did not change. A transparent monolayer film 25 mu m thick was produced again.

Example 3:

Extrusion and subsequent increasing orientation in the longitudinal and lateral directions resulted in an opaque single layer PLA film having a thickness of 30 μm. About 95% by weight of this layer consists of polyacet with a melting point of 135 ° C., a melt flow index of about 3 g / 10 min and a glass transition temperature of 60 ° C., and about 5% by weight of COC (Ticona Topas) with a Tg of 140 ° C. 6013). The layer further comprises stabilizers and neutralizers in conventional amounts. The manufacturing conditions at the individual procedure steps are:

Extrusion: temperature 170-200 ℃

Temperature of discharge roller: 60 ℃

Longitudinal stretching: temperature 68 ℃

Portrait draw ratio: 4.0

Lateral drawing: temperature 88 ℃

Lateral draw ratio (effective): 5.5

Setting: Temperature: 75 ° C

Convergence: 5%

In this way, an opaque film with a characteristic nacreous gloss and a reduced density of about 0.75 g / cm 3 was obtained.

The film is injected into a commercial tobacco packaging machine as an inner liner and can be used without major problems. Non-vacuolated films according to Examples 1 and 2 have been found to be particularly advantageous.

In contrast, biaxially oriented polypropylene films were not suitable for this use. Due to the strong reset force of the material, individual cigarettes could not be packaged.

As described in detail, the present invention is used in tobacco wrappers comprising at least one outer wrapper and an inner wrapper for tobacco.

Claims (16)

A method of using a biaxially oriented monolayer or multilayer film as an inner liner of tobacco wrappers, Wherein the film comprises 70 to 100% by weight of at least one aliphatic polyhydroxycarboxylic acid polymer. The method of claim 1, wherein the film is transparent. The method of claim 1, wherein the film is white. The method of claim 1, wherein the film is an opaque, vacuolated base layer. 5. The method of claim 1, wherein the film is metallized on one surface. 6. 5. The method of claim 1, wherein the film is metallized on both surfaces. 6. 7. The method of claim 1, wherein the film is embossed. 8. 6. The method of claim 5, wherein the metallized surface of the film is embossed. The method of claim 1, wherein the film comprises less than 80 to 98 weight percent of an aliphatic polyhydroxycarboxylic acid polymer in the base layer. 10. The film of claim 1, wherein the film is characterized by an upper layer on both sides, the upper layer comprising between 70 and <100% by weight of an aliphatic polycarboxylic acid polymer. 11. How to use. The method according to any one of claims 1 to 10, wherein the aliphatic polyhydroxycarboxylic acid is polyacetic acid. The method according to any one of the preceding claims, wherein the total thickness of the film is at least 20 to 100 μm. The method of claim 1, wherein the thickness of the top layer is 0.5 to 6 μm. 14. A method according to any one of the preceding claims, wherein the top layer is sealable. The method of claim 1, wherein the tobacco wrapper is a flip pack. The method according to any one of the preceding claims, wherein the tobacco wrapper is a soft wrapper.